Absorbent structures comprising coated super-absorbent polymer particles

• US 7,108,916 B2
• Filed: 06/30/2004
• Issued: 09/19/2006
• Est. Priority Date: 06/30/2003
• Status: Active Grant

• Current Assignee: The Procter & Gamble Company
• Original Assignee: The Procter & Gamble Company
• Inventors: Ehrnsperger, Bruno Johannes, Opper, Heike, Schoenborn, Udo Friedel
• Primary Examiner(s): LE, HOA T
• Application Number:
  US10/881,090
• Publication Number:
  US 20050003191A1
• Time in Patent Office: 811 Days
• Field of Search: 428/403, 428/407
• US Class Current: 428/403
• CPC Class Codes: A61L 15/42 Use of materials characterised by their function or physical properties liquid bandages A61L26/00
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: C08J 2300/14 Water soluble or water swellable polymers, e.g. aqueous gels
• CPC Class Codes: C08J 2333/02 Homopolymers or copolymers of acids; Metal or ammonium salts thereof
• CPC Class Codes: C08J 3/128 Polymer particles coated by inorganic and non-macromolecular organic compounds
• CPC Class Codes: Y10T 428/2991 Coated

Abstract

This invention is directed to super-absorbent material, which comprises a super absorbent polymer core that is coated with an organic, polar coating agent, and whereby the particulate super-absorbent material has a contact angle and a corresponding cos CA_m (as defined herein), whereby the cos CA_m is more than 0.3, and whereby, when said coating agent is in the form of particles, said coating agent particles have a (weight) mean particle size of from 0.001 to 1 micron. The material is useful for absorbent structures and absorbent articles (comprising such structures). The coated super-absorbent material is typically present in said absorbent structure at least at a concentration of 50% by weight of the structure, preferably even 80% or even 90%. The invention also provides a process for making the absorbent material.

Claims

1. A particulate super-absorbent material comprising a particulate core of super-absorbent polymers, said particulate core coated with a coating agent consisting essentially of an organic coating compound having from 2 to 14 carbon atoms which has one or more polar groups, wherein the particulate super-absorbent material has a contact angle and a corresponding cos CA_m, wherein the cos CA_m is greater than 0.3 and wherein said coating agent is the form of particles, said particles having a mean particle size of from 0.001 to 1 micron.

2. The particulate super-absorbent material according to claim 1 wherein said particulate core of super-absorbent polymer, before being coated with said coating agent, has a contact angle CA_p and a cos CA_p and the particulate super-absorbent material has a contact angle CA_m and a cos CA_m, wherein the ratio cos CA_m/cos CA_p is at least 1.5.

3. The particulate super-absorbent material according to claim 1 wherein said coating agent comprises an organic material having from 2 to 9 carbon atoms.

4. The particulate super-absorbent material according to claim 1 wherein said polar groups are selected from the group consisting of a hydroxyl group, a carboxylic acid polar group, sulphonic acid polar group, a phosphoric acid polar group, and combinations thereof.

5. The particulate super-absorbent material according to claim 1 wherein said particulate core of super-absorbent polymers has a mean particle size from 200 to 500 microns.

6. The particulate super-absorbent material according to claim 1 wherein at least part of said super-absorbent polymers are cross-linked to one another.

7. The particulate super-absorbent material according to claim 1 wherein said super-absorbent polymers are selected from the group consisting of water-swelling polyacrylates and derivatives, gelling polyacrylates and derivatives, and combinations thereof.

8. The particulate super-absorbent material according to claim 1 wherein the coating agent comprises an organic compound having a molecular weight of less than 500 g/mol.

9. The particulate super-absorbent material according to claim 1 wherein said particulate super-absorbent material comprises from 0.05% to 3%, by weight, of the coating agent.

10. The particulate super-absorbent material according to claim 1, wherein said particulate super-absorbent material exhibits a 20 cm FHA value of at least 20g/g.

11. The particulate super-absorbent material according to claim 1, wherein said super-absorbent material has a FHA_coated(20 cm), wherein said super-absorbent polymer has a FHA_uncoated (20 cm), and wherein a ratio of FHA_coated (20 cm) to FHA_uncoated (20 cm) is at least about 1.05.

12. A particulate super-absorbent material comprising a particulate core of super-absorbent polymers, said particulate core coated with a coating agent consisting essentially of an organic coating compound having from 2 to 14 carbon atoms which has one or more polar groups, wherein said coating agent of said particulate super-absorbent material provides a surface tension reduction of less than 10% and wherein said coating agent is in the form of particles having weight mean particle size of from 0.001 to 1 micron.